extend policies configuration

[wkloucek]

#203 added support for the policies service.

We should allow to configure policies from an external configmap additionally to here:

ocis-charts/charts/ocis/values.yaml

Lines 317 to 321 in 1a85f03

	# -- Sets the policies. Each policy is defined by a `fileName` and a `content`. The content takes the rego script as text, see
	# https://doc.owncloud.com/ocis/next/deployment/services/s-list/policies.html#example-policies
	# Attention: All scripts provided here will end up in a ConfigMap. The data stored in a ConfigMap cannot exceed 1 MiB. see
	# https://kubernetes.io/docs/concepts/configuration/configmap/#:~:text=The%20data%20stored%20in%20a,separate%20database%20or%20file%20service.
	policies: []

This was not possible when #203 was crated, see #203 (comment)